Bacterial Shapes and Arrangements

streptococci

chainlike pattern of spherical bacteria

streptobacilli

chains of rod-shaped bacteria

3 basic shapes

coccus, bacillus, spiral

spiral

cylinder, twisty, never straight

staphylococci

grapelike clusters of broad sheets of spherical bacteria

tetrads

groups of four spherical bacteria

bacterial size

micrometer is used to measure size

diplococci

pairs of spherical bacteria

bacillus

rod-shaped

coccobacilli

short, plump oval looking, partly rod-shaped but also spherical

coccus (pl. cocci)

spherical, circles

arrangements of bacillus

streptobacilli, coccobacilli

arrangements of cocci

streptococcus, staphylococcus, diplococci, tetrad

vibrio

type of spiral bacteria; curved or bent rods

spirochete

type of spiral bacteria; helical and flexible; move by means of axial filaments (resemble flagella but are contained within a flexible external sheath

spirilla

type of spiral bacteria; helical shape; like a corkscrew, and fairly rigid bodies; move with whiplike external appendages called flagella

arrangements of spiral

vibrio, spirillum, spirochete